Note 3 at Ac 10:45: Some scholars speculate that this took place as many as ten years after the Day of Pentecost. Certainly, Peter, and possibly some of these other Jews, had been born again and walking with the Lord for a long time in such close relationship that his shadow had healed people (Ac 5:15) and others had been raised from the dead (Ac 9:41). Yet they were totally surprised to see God's acceptance of the Gentiles, even though it was clearly prophesied in Old Testament scriptures (Isa 11:10, 42:6, 49:6, 22, 60:3-16, 62:2, 66:19; Jer 16:19-21; and Mal 1:11) and Jesus Himself spoke of it (Mt 8:11-12, 21:42-43; Lu 4:25-27, 13:29; and Joh 10:16).

This illustrates that the Lord doesn't bring us into all truth instantly; there is a growth process (Isa 28:10). All believers have enough "blind spots" that we have no right to adopt a know-it-all attitude. "If any man think that he knoweth any thing, he knoweth nothing yet as he ought to know" (1Co 8:2).